Let's call Maria 'M' and Sal 'S'
Maria is 12 1/2 years older than Sal.
S + 12 1/2 = M
The sum of their ages is 28 1/2
S + M = 28 1/2
Solve for M in the second equation:
28 1/2 - S = M
The first equation is:
S + 12 1/2 = M
Set them equal to each other since they both are equal to M.
28 1/2 - S = S + 12 1/2
Basicaly, n = S, so your correct answer is B. 28 1/2 - n = n + 12 1/2
